Facile synthesis of Fe3O4/CoCO3 nanoparticles anchored on reduced graphene oxide for highly efficient microwave absorption

In this work, the composites comprising Fe3O4/CoCO3 nanoparticles and reduced graphene oxide (rGO) with hierarchical structure have been synthesized using a one-pot solvothermal method. The microstructure and microwave absorption properties of Fe3O4/CoCO3@rGO were thoroughly analyzed across varying amounts of rGO. Microstructural analysis confirms the successful synthesis of the Fe3O4/CoCO3@rGO composites, illustrating Fe3O4/CoCO3 nanoparticles firmly attached to the surface of rGO nanosheets. It is found that the incorporation of rGO leads to a significant increase in both the real and imaginary parts of permittivity, while the permeability marginally decreases due to the non-magnetic nature of rGO. The effective interplay of electromagnetic parameters facilitates the optimization of material impedance matching and bolsters its microwave attenuation capability. In the sample S3 with 25 wt% filler incorporated into the paraffin matrix, a minimum reflection loss of - 24.4 dB is attained at 14.64 GHz with an absorber thickness of 2.3 mm, featuring an effective absorption bandwidth (below - 10 dB) spanning 6.24 GHz (11.76-18 GHz). Likewise, the sample S4, also with a 25 wt% filling rate, exhibits an exceptionally wide effective absorption bandwidth of 6.56 GHz (11.44-18 GHz) at a slender matching thickness of 2.1 mm, encompassing the entire Ku band and a portion of the X band. Furthermore, an absorption peak of - 32.4 dB was noted at 13.68 GHz with a thickness of merely 1.8 mm. The remarkable microwave absorption performance of the Fe3O4/CoCO3@rGO composite materials primarily stems from the synergistic complementary effects of dipole polarization, interface polarization, conductive loss, and magnetic loss. These findings underscore that Fe3O4/CoCO3@rGO composites serve as a valuable reference for the development of high-performance microwave absorbers with the requirements of lightweight, strong absorption and bandwidth.